Warwick Water Hardness & Quality Report (2026)

Warwick, the historic county town of Warwickshire on the River Avon, is supplied by Severn Trent Water from the River Avon catchment and the Jurassic Limestone of the Warwickshire plateau. The River Avon at Warwick drains the south Midlands — the Jurassic Blue Lias and White Lias limestone country of south Warwickshire and Gloucestershire — carrying moderate dissolved calcium from Jurassic carbonate dissolution. Severn Trent also draws from the Triassic Mercia Mudstone and Triassic Sherwood Sandstone aquifers of the Warwickshire plain, and possibly from the Jurassic limestone groundwater of the south Warwickshire plateau. The blend produces a moderately hard supply typical of the Shakespeare Country supply zone served from the Avon valley distribution network.

Warwick's hardness of 166.5 mg/L (11.7°Clark) reflects the blend of River Avon Jurassic limestone catchment and Triassic/Jurassic groundwater in Severn Trent's Warwickshire supply zone. The Drinking Water Inspectorate (DWI) classifies this supply as moderately hard.

Limescale is a regular household concern in Warwick. At 166.5 mg/L, limescale forms in kettles within three to four weeks and monthly descaling is sensible. Combi-boiler heat exchangers accumulate deposits at a moderate rate; annual servicing is recommended. Showerheads and taps develop regular deposits. Washing-up liquid lathers moderately. Using Calgon monthly in the washing machine and a regular descaling routine is appropriate limescale management for Warwick households.